A clam dredged up off the coast of Iceland is thought to have been the longest-lived creature discovered.

Scientists said the mollusc, an ocean quahog clam, was aged between 405 and 410 years and could offer insights into the secrets of longevity.

Researchers from Bangor University in north Wales said they calculated its age by counting rings on its shell.

According to the Guinness Book of Records, the longest-lived animal was an Arctica clam found in 1982 aged 220.

Unofficially, another clam - found in an Icelandic museum - was discovered to be 374-years-old, Bangor University said, making their clam at least 31 years older.

The clam, nicknamed Ming after the Chinese dynasty in power when it was born, was in its infancy when Queen Elizabeth I was on the throne and Shakespeare was writing plays such as Othello and Hamlet.

Professor Chris Richardson, from Bangor University's School of Ocean Sciences, told the BBC: "The growth-increments themselves provide a record of how the animal has varied in its growth-rate from year to year, and that varies according to climate, sea-water temperature and food supply.

"And so by looking at these molluscs we can reconstruct the environment the animals grew in. They are like tiny tape-recorders, in effect, sitting on the sea-bed and integrating signals about water temperature and food over time."

'Escaping' old age

Prof Richardson said the clam's discovery could help shed light on how some animals can live to extraordinary ages.

"What's intriguing the Bangor group is how these animals have actually managed, in effect, to escape senescence [growing old]," he said.

"One of the reasons we think is that the animals have got some difference in cell turnover rates that we would associate with much shorter-lived animals."

He said the university had received money from the UK charity Help The Aged to help fund its research.